Junctional Epidermolysis Bullosa, Severe (LAMB3-Related)
Summary
Junctional epidermolysis bullosa (JEB) is a severe skin fragility condition where the skin blisters and tears with minimal friction or trauma. LAMB3 encodes one subunit of laminin-332, a protein that anchors the outer skin layer (epidermis) to the underlying tissue. Without functional laminin-332, the skin layers separate at the junction — hence "junctional."
Practical takeaway
Given the rarity, partner carrier risk is very low. Carrier testing available if desired. Realised does not calculate reproductive risk or advise on reproductive decisions.
Evidence detail
What Carrier Status Means For You
You are not affected. One working copy of LAMB3 produces sufficient laminin-332. Standard 25/50/25 recessive inheritance applies.
Population Context
JEB occurs across all populations at approximately 1 in 500,000 births. No dramatic population-specific enrichment. R635X is the most common pathogenic variant worldwide.
Limitations
23andMe tests 3 LAMB3 variants. JEB can also be caused by variants in LAMA3, LAMC2, and COL17A1. Comprehensive EB panels cover all relevant genes.